/*
 * Copyright � 2002-2011 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Reflection;

namespace Spring.Core;

/// <summary>
/// Criteria that is satisfied if the number of parameters to a given
/// <see cref="System.Reflection.MethodBase"/> matches an arbitrary number.
/// </summary>
/// <remarks>
/// <p>
/// This class supports checking the parameter count of both methods and
/// constructors.
/// </p>
/// <p>
/// Default parameters, etc need to taken into account.
/// </p>
/// </remarks>
/// <author>Rick Evans</author>
public class MethodParametersCountCriteria : ICriteria
{
    /// <summary>
    /// Creates a new instance of the
    /// <see cref="MethodParametersCountCriteria"/> class.
    /// </summary>
    /// <remarks>
    /// <p>
    /// This constructor sets the
    /// <see cref="MethodParametersCountCriteria.ExpectedParameterCount"/>
    /// property to zero (0).
    /// </p>
    /// </remarks>
    public MethodParametersCountCriteria() : this(0)
    {
    }

    /// <summary>
    /// Creates a new instance of the
    /// <see cref="MethodParametersCountCriteria"/> class.
    /// </summary>
    /// <param name="expectedParameterCount">
    /// The number of parameters that a <see cref="System.Reflection.MethodInfo"/>
    /// must have to satisfy this criteria.
    /// </param>
    /// <exception cref="System.ArgumentException">
    /// If the supplied <paramref name="expectedParameterCount"/> is less
    /// than zero.
    /// </exception>
    public MethodParametersCountCriteria(int expectedParameterCount)
    {
        ExpectedParameterCount = expectedParameterCount;
    }

    /// <summary>
    /// The number of parameters that a <see cref="System.Reflection.MethodInfo"/>
    /// must have to satisfy this criteria.
    /// </summary>
    /// <exception cref="System.ArgumentException">
    /// If the supplied value is less than zero.
    /// </exception>
    public int ExpectedParameterCount
    {
        get { return _count; }
        set
        {
            if (value < 0)
            {
                throw new ArgumentOutOfRangeException(
                    "value", value, "Cannot specify a parameter count of less than zero.");
            }

            _count = value;
        }
    }

    /// <summary>
    /// Does the supplied <paramref name="datum"/> satisfy the criteria encapsulated by
    /// this instance?
    /// </summary>
    /// <param name="datum">The datum to be checked by this criteria instance.</param>
    /// <returns>
    /// True if the supplied <paramref name="datum"/> satisfies the criteria encapsulated
    /// by this instance; false if not or the supplied <paramref name="datum"/> is null.
    /// </returns>
    public bool IsSatisfied(object datum)
    {
        bool satisfied = false;
        MethodBase method = datum as MethodBase;
        if (method != null)
        {
            ParameterInfo[] parameters = method.GetParameters();
            if (parameters.Length == ExpectedParameterCount)
            {
                satisfied = true;
            }
            else if ((parameters.Length > 0) && (ExpectedParameterCount >= parameters.Length - 1))
            {
                ParameterInfo lastParameter = parameters[parameters.Length - 1];
                satisfied = lastParameter.GetCustomAttributes(typeof(ParamArrayAttribute), false).Length > 0;
            }
        }

        return satisfied;
    }

    private int _count;
}
